The growth of gallium nitride films produced by reactive sputtering at lowtemperature

Radio frequency reactive sputtering was used to produce nano-crystalline ga llium nitride films on glass and silicon substrates at room temperature. Th e effects of varying the N-2:Ar sputtering gas ratio were investigated. Fil ms characterised by Raman and FTIR spectroscopy. which showed the presence of A,(LO) and EI(TO) phonon modes, respectively, confirmed that alpha-GaN h ad been produced. The shift in position of the Raman peak from the bulk val ue indicated that the material was nano-crystalline, which was confirmed by TEM observations. Alms grown on glass substrates had a greater peak shift indicating a smaller crystallite size. The variation in E-1(TO) peak width with sputtering atmosphere composition indicated an optimal sputtering atmo sphere of approximate to 30% N-2:70% Ar. Optical absorption studies were pe rformed to characterise film properties and obtain band gap values. A minim um in the Raman peak width was observed for films grown on silicon with a R aman shift of 728 cm(-1) and indicated a reduction in the crystallite size distribution.